TMHP01 Student Project autumn 2013
Secondary controlled hydrostatic
transmission for pendulum arm forwarder
Forwarders are heavy vehicles used to haul timber in the forest. Increased
demands on productivity, working environment for the driver and lowered
impacts on the surroundings have resulted in a need to equally distribute
tractive and normal contact forces on as many wheels as possible as well
as a need to isolate the driver from the ground topography. One way of
solving this is by using pendulum arms that can control the height on
each wheel individually. The aim of this project is to develop a
hydrostatic transmission control for such a forwarder.
System description
Secondary control
• Three-bodied vehicle with six wheels and two
steering joints.
• Constant pressure controlled pump.
• Output velocity controlled via
displacement setting.
the
motor
Secondary controlled circuit.
Drive cycle results
Pendulum arm.
Sketch of forwarder body.
• Two closed hydraulic circuits with three motors
and one pump each.
Hydraulic transmission circuit.
• Chosen concept works as a hydraulic differential.
• Can handle velocity compensation in both
turning motion and during pendulum arm
movement
Velocity compensation in turning motion and
obstacle (at 5 s).
IEI – Department of Management and Engineering
Division of Fluid and Mechatronic System
K. Viktor
Larsson
L. Viktor
Larsson
Fredrik
Henriksen
Jan
Malecki